Does this loadcell's creep mean that I can not let a constant load on the loadcell?
Typical creep (parameter "1") of a Vishay load cell over the stated 30 minute interval. 



The Vishay document states:


  OIML recommendation R76 requires a 30 minute test and
  specifies an error limit for this time period, as well as the
  last 10 minutes (20 to 30 minutes). NTEP requires a one
  hour test and specifies an error limit for this period.


OIML is "Organization Internationale de Metrologie Legale" (International Organization of Legal Metrology) European standard. 

NTEP is "National Type Evaluation Program" of NIST (National Institute of Standards and Technology) US standard. 

You might expect inexpensive load cells would not have full accuracy specifications for "Trade" use, but most should behave reasonably and not creep much after the first 10-20 minutes.