In June 2007, AZ reached a deal concerning a loan involving Lens; it meant he would play the 2007–08 season for NEC, and that he would return to AZ the season afterwards. Lens agreed with the deal, and the player officially joined NEC on loan in the summer of 2007.

In July 2008, Lens had an operation on his left foot, which meant he was out for some time. The 2008–09 season was a personal disappointment for Lens, who did not contribute much to AZ’s championship win. When head coach Louis van Gaal left the team for Bayern Munich, Lens saw a chance for himself to play more matches. He grabbed the chance under the new coach, and he played well and scored important goals for AZ.

Although Lens previously played for the Netherlands under-21 team, he chose to play for the Suriname national team, since he said he felt like he is Surinamese. In 2009, Lens was called up for Suriname’s squad by national team coach Wensley Bundel, for the Parbo Bier Cup. He scored two goals in three matches and helped Suriname finish second in the tournament.

On 21 May 2010, PSV contracted Lens for four years, swapping Dirk Marcellis as part of the deal. Lens was given the number 9 shirt, and his first year at the club was a successful one for the player. He was moved from a central position to the flanks, being more utilised on both wings or working behind strikers as a second striker. He struggled to score in first few matches, but eventually became used to the new position. He reached the Europa League quarter-finals with the team, scoring 3 goals in 11 appearances, and reached 10 Eredivisie goals in 33 appearances, while the Eindhoven-based team only finished in third place, despite being the table leaders for the most of the 2010–11 season.

On 3 May 2010, Lens was called up for the Dutch national team, as a part of the preparations for the 2010 FIFA World Cup. However, on 27 May 2010, Netherlands manager Bert van Marwijk announced that the player would not be part of the final 23-man squad participating in the competition. On 11 August 2010, Lens made his debut in a 1–1 friendly draw with Ukraine, scoring the only goal for the Oranje.

At the beginning of the 2011–12 season, Lens’ jersey number was changed to number 11, which was free since the departure of Nordin Amrabat to Kayserispor in January 2011. On 6 November 2011, Lens came in from the bench against Heracles and scored a hat-trick, his first for the club.

On 18 June 2013, Lens signed a four-year contract with Ukrainian club Dynamo Kyiv. On 29 August, he scored his first official goal for Dynamo, opening the score on the ninth minute of a 5–1 victory over Kazakhstani club Aktobe in the UEFA Europa League play-offs second leg, an 8–3 aggregate win. On 6 October, Lens scored his first two goals in the Ukrainian Premier League in a crushing 9–1 victory over Metalurh Donetsk. He helped Dynamo win the Ukrainian Cup in his first season.

On 23 April 2015, Lens was sent off for two bookings in the first half, as Dynamo lost 0–2 at Fiorentina and were eliminated from the quarter-finals of the Europa League. His second yellow card was when the referee judged that he had dived in the penalty area. In his second and final season for Dynamo, he managed to help his team win both the Premier League and Ukrainian Cup without suffering a single defeat in both competitions.

On 15 July 2015, after completing a medical, Sunderland signed Lens for an undisclosed fee on a four-year contract. This move reunited him with head coach Dick Advocaat after previously working under him at PSV and AZ.

Lens scored his first English Premier League goal on 29 August 2015, securing a 2–2 draw at Aston Villa. He scored his second Sunderland goal against West Ham United on 3 October 2015, lobbing the ball over goalkeeper Adrián to put Sunderland 2–0 ahead. However, Lens was then sent off after receiving two yellow cards for rash tackles, and West Ham went on to earn a 2–2 draw. The match turned out to be Advocaat’s final one in charge of Sunderland, as he left the club the next day.

On 30 August 2016, Lens was loaned to Fenerbahçe on a season-long deal.

On 6 August 2017, Beşiktaş signed Lens on loan, with the option of a permanent transfer afterwards. He scored his debut goal for the club in a 2–2 draw against Trabzonspor. Playing as a replacement for Ricardo Quaresma, he managed to find the net in the 58th minute of the match. On 7 June 2018, it was confirmed that Lens had signed four years contract for Beşiktaş.