It's not true. Lend-Lease didn't make any stipulations regarding de-colonization, and Britain kept several colonies for decades after WWII ended (e.g. Hong Kong, Aden, etc.).

The closest thing to what you're talking about is the September 1940 "Destroyers for Bases" deal, where FDR used an executive directive to give the British 50 obsolescent destroyers in exchange for 99 year leases on several British air and naval bases in the Caribbean (some of which were still in U.S. use until the 1990s, although most were closed post-war). Even this was a win-win for the British, since passing these bases off to the Yanks allowed them to commit less manpower to manning far-off outposts and divert these men to the main war effort, instead.